Electronic systems can include components that rely on a regulated power source. Power converter circuitry can be used to provide a circuit supply rail having the regulated voltage. Linear regulators, sometimes called LDOs employ one method of providing a regulated voltage for electronic systems. Linear regulators can provide both high power supply rejection ratio (PSRR) and low output noise performance, and are widely used to power up noise sensitive rails, such as, but not limited to, power rails for analog-to-digital converters (ADCs), digital-to-analog converters (DACs) and radio frequency (RF) circuits. (e.g. ADC, DAC, RF, etc.) DC-to-DC switched-mode voltage converters can also be used to provide a regulated DC voltage. DC-to-DC switched-mode voltage converters can usually provide better efficiency compared to an LDO. In order to capture the advantages of both systems, some popular analog signal-chain system power designs combine a DC-to-DC switched-mode voltage converter with an LDO.
As the signal-chain systems continue to evolve, more complexity systems have been packed into smaller solution sizes. In addition, integrated circuit core supply voltages have been moving down in order to save the power consumption in the evolving low geometry process. However, use of traditional P-Channel linear regulators has become more difficult as the lower input voltages do not provide enough gate turn-on voltage.